This invention relates, in general, to lancing design in industrial applications, and more particularly, to improving the combustion-enhancing characteristics of gases lanced into combustion environments.
Lancing is a process used to improve combustion in industrial applications. Typically, lancing involves injecting gas into a primary flame or fuel stream so as to maintain flame stability and aid the fuel ignition process. This is especially true for applications such as rotary kilns, where low quality fuels are often used and dust is present in large quantities in the flame neighborhood. Oxygen is commonly used as a lancing gas in these applications.
Ideally, the exposure of the lanced gas to the primary flame or fuel stream is at a maximum. In order to obtain maximum exposure, the lanced gas must penetrate far into the fuel environment and sweep over the fuel jet over a wide area. Thus, high velocity lances are traditionally employed, which have the disadvantage of often entraining a large volume of the surrounding medium. In many combustion applications, the entrainment of flue gases, nitrogen, particulates, and dust can reduce the lanced gas concentration. Thus, it is more difficult to maintain uniform flame temperature profiles and ideal combustion conditions.
Furthermore, high velocity lances can require high supply pressures and high operating costs. In addition, high velocity lances can create high particulate and NOx emissions, and can increase safety risks, as the high velocities at the lance exit increase the chances of premature ignition.
Accordingly, there is a need for a lancing process that transports the lanced gas a greater distance and sweeps over the fuel jet over a wide area, while having greater injected gas concentration. Moreover, there is a need for a cost-effective lancing process that does not require high velocities or high supply pressures and that does not pose environmental or safety risks.